In vivo/in vivo Method

  1. 1 mg of Sn²⁺ in the form of pyrophosphate (“cold PYP”) is given IV

  2.  20 min wait  to permit mixing of the Sn PYP in body and diffusion of Sn²⁺ into RBC.

  3.  IV injection of 25 mCi  ^99mTc pertechnetate

4.  10 min waiting period to permit diffusion of pertechnetate into RBC's where radiolabeling takes place.

  5. Expected labeling efficiency: 80-85%

InVivo / InVivo: Advantages / Disadvantages

  Advantages: quick, simple, inexpensive

  Disadvantage: lowest labeling efficiency of all commonly used procedures, but perfectly acceptable for routine work, e.g., MUGAs.